1. Field of the Invention
The present invention relates to an alignment layer for a display device, a liquid crystal display device including the same, and a method and apparatus for treating the same, and more particularly to a rubbed alignment layer for a display device, a liquid crystal display device including the rubbed alignment layer, and a method and apparatus for rubbing the alignment layer.
2. Description of the Related Art
A liquid crystal display device is a display device for controlling light retardation by causing a change in the refractive index of liquid crystals such that alignment of the liquid crystals is changed according to a potential difference between a voltage applied to a common electrode and a voltage applied to a pixel electrode. In order to improve a response speed of the liquid crystal display device by imparting a predetermined direction to liquid crystals and to increase visibility of the liquid crystal display device, the liquid crystal display device may include an alignment layer formed on a surface contacting a liquid crystal layer of an upper or lower substrate of a liquid crystal panel.
In order to orient the liquid crystals, the alignment layer may be treated by, for example, rubbing, oblique deposition, polymer stretching, optical alignment, ion beam irradiation, and so on. Among others, the rubbing is to treat the alignment layer by rubbing or abrading a surface of the alignment layer in a desired direction using a rubbing member.
Since liquid crystal particles have an index of refraction anisotropy, the liquid crystal display device may display different images according to the viewer's observation angle. In order to widen the viewing angle of a liquid crystal display device, the liquid crystal display device may include a plurality of domains. Compared to a liquid crystal display device having a single domain, the liquid crystal display device having multiple domains may have a reduced difference in the average refractive indices of liquid crystal particles viewed according to the viewing angle, thereby achieving widening of the viewing angle of the liquid crystal display device.
In order to multiply domains, several approaches, including adjusting electrode patterns, forming protrusions for separating domains, etc., may be attempted. However, these approaches are very complicated and may affect display characteristics, for example, brightness.